Japanese investment bank Nomura had been cited as a potential buyer for water utility Southern Water, owned by Scottish Power.
But a source close to the bank said there was nothing going on and that a deal was unlikely.
Italian power group Enel has also been touted as a potential buyer for Southern Water, as has Spanish utility Endesa.
A spokesman for Scottish Power said the company was looking to refinance Southern Water or sell it. Scottish Power bought the utility for £1.7bn in 1996 and has appointed CSFB as advisors.
Last year, Nomura failed to in its attempt to buy Welsh utility Hyder.